Direct detection of odd-frequency superconductivity via time- and angle-resolved photoelectron fluctuation spectroscopy

TL;DR

This paper proposes a novel experimental method using time- and angle-resolved photoelectron fluctuation spectroscopy to directly detect odd-frequency superconductivity by analyzing momentum-resolved electron correlations.

Contribution

It introduces a new measurement scheme that directly probes the hidden order parameter of odd-frequency pairing in superconductors.

Findings

Correlation signals are proportional to the square of the anomalous Green's function.

The scheme can detect the hidden order parameter of odd-frequency pairing.

Application demonstrated on a two-band superconductor.

Abstract

We propose a measurement scheme to directly detect odd-frequency superconductivity via time- and angle-resolved photoelectron fluctuation spectroscopy. The scheme includes two consecutive, non-overlapping probe pulses applied to a superconducting sample. The photoemitted electrons are collected in a momentum-resolved fashion. Correlations between signals with opposite momenta are analyzed. Remarkably, these correlations are directly proportional to the absolute square of the time-ordered anomalous Green's function of the superconductor. This setup allows for the direct detection of the "hidden order parameter" of odd-frequency pairing. We illustrate this general scheme by analyzing the signal for the prototypical case of a two-band superconductor.